Improve Visualizer behavior

This change include:
- Hide parent proxy when creating a new filter
- Automatically activate the newly created filter
- Add Opacity control to any filter
- Properly handle domain default properties

Change-Id: I88184734e4e337817743a9a4f9da8b5fbf3e2ee2
Merge topic 'pvweb-visualizer' into next

bfb0af7c Improve Visualizer behavior